CN107983391A - Insoluble magnetic cobalt/defective g-C3N4 composite catalysts and its application in Oxone degrading waste waters are catalyzed - Google Patents

Abstract

The invention discloses an insoluble magnetic cobalt/defective g- _{C3N4 composite} catalyst and its application in catalyzing Oxone degradation wastewater, belonging to the technical field of synthesis of composite catalytic materials and catalytic degradation of organic wastewater. The main points of the technical scheme of the present invention are: the preparation method of insoluble magnetic cobalt/defective g-C ₃ N ₄ composite catalyst, specifically including the preparation of a magnetic cobalt catalyst with a mass percentage of cobalt of 11% and a mass percentage of cobalt It is the preparation steps of 1.2% insoluble magnetic cobalt/defective g-C ₃ N ₄ composite catalyst, the insoluble magnetic cobalt/defective g-C ₃ N ₄ composite catalyst can efficiently catalyze Oxone to degrade levofloxacin wastewater. The insoluble magnetic cobalt/defective g-C ₃ N ₄ composite catalyst prepared by the present invention has better insolubility in neutral environment, has better catalytic performance at the same time, and also has certain photocatalytic performance, can be applied to Degradation of Refractory Biodegradable Organic Pollutants.

Description

Insoluble Magnetic Cobalt/Defective g-C3N4 Composite Catalysts and Their Effects on Catalytic Oxone Drop application in waste water

technical field

The invention belongs to the technical field of synthesis _of composite catalytic materials and catalytic degradation of organic wastewater, and in particular relates to a preparation method of an insoluble magnetic cobalt/defective _gC3N4 composite catalyst and its application in catalytic Oxone degradation of levofloxacin wastewater.

Background technique

Levofloxacin is an antibiotic drug with optical activity among quinolones. It has obvious inhibitory effect on most Gram-positive bacteria and Gram-negative bacteria, and the effect is long-lasting. Therefore, levofloxacin has been widely used clinically. Due to their long half-lives, traditional water treatment techniques cannot effectively remove these drugs, so their potential harm to public health has attracted widespread attention.

Oxone (2KHSO ₅ KHSO ₄ K ₂ SO ₄ ) is the trade name of potassium hydrogen peroxosulfate complex salt, and its active substance is potassium monoperoxohydrogensulfate KHSO ₅ , which forms asymmetric peroxidation due to the substitution of HOOH by one SO ₃ ⁻ The unique structure of the substance makes it easy to stimulate and generate a large number of sulfate radicals (SO ₄ ^•- ). Oxone/Co ²⁺ is an oxidation system similar to Fenton's reagent. Transition metal Co ²⁺ can catalyze Oxone to generate a large number of active, strong oxidation ability and non-selective SO ₄ ^•- free radicals, which can reduce organic pollution in water Substances are completely oxidized to CO ₂ , H ₂ O and inorganic salts. Due to its high treatment efficiency, especially its excellent performance in the removal of refractory biodegradable pollutants, this technology has always been a research hotspot.

Graphite carbon nitride (gC ₃ N ₄ ) is a unique 2D layered non-metallic material, and its energy band structure is very suitable for the two key half-reaction steps of hydrogen production and oxygen production in photocatalytic decomposition of water. Due to the advantages of simple method and good thermal stability, it is generally regarded as a photocatalytic material with broad application prospects. It has important research value in the fields of photocatalytic water splitting to produce hydrogen, artificial photosynthesis, degradation of organic pollutants, and carbon dioxide reduction.

In the Oxone/Co ²⁺ oxidation system, water-soluble cobalt sulfate is often used as a catalyst. Cobalt sulfate will be ionized into Co ²⁺ in the aqueous solution. During the reaction, Co ²⁺ as a catalyst can promote the massive generation of SO ₄ ^•- free radicals. Thereby ensuring the smooth progress of the oxidation reaction. Soluble cobalt salts will be discharged with water after the reaction is completed. However, cobalt is a heavy metal element that can be enriched in organisms and accumulate in the human body through the food chain, so it is potentially harmful to the ecological environment and human health. Experimental studies have found that the Oxone/Co ²⁺ oxidation system has no requirement on the pH value of wastewater treatment, and in most cases the treatment effect on neutral wastewater is better. Therefore in order to avoid the pollution of soluble heavy metal cobalt, in the present invention, take melamine, sodium hydroxide, ferrous sulfate, ferric chloride and cobalt sulfate as raw material, have prepared and have not found in literature, insoluble in neutral environment Aqueous, recyclable insoluble magnetic cobalt/defective _{gC3N4 composite} catalysts.

Contents of the invention

The technical problem that the present invention solves is to provide a kind of preparation method of insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst and its application in catalytic Oxone degradation levofloxacin wastewater, the insoluble magnetic cobalt/defective gC that this method makes The oxidation system composed of ₃ N ₄ composite catalyst and Oxone can not only effectively degrade levofloxacin wastewater, but also the insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst can be recycled and reused to avoid secondary pollution to the environment.

The present invention adopts following technical scheme for solving the above-mentioned technical problem, the preparation method of insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst, it is characterized in that concrete steps are:

(1) Dissolve 2.703g FeCl ₃ 6H ₂ O, 2.780g FeSO ₄ 7H ₂ O and 6.033g CoSO ₄ 7H ₂ O in 20mL of deionized water. After the dissolution is complete, an orange-red mixed solution is obtained. The above mixed solution Put it in a water bath and heat it to 60°C and add it dropwise to 45mL of ammonia solution with a molar concentration of 3mol/L. During the reaction, black solids are produced. After the reaction, the turbid liquid containing a large amount of black solids is ultrasonically Ultrasound at 60°C for 30 minutes under the same conditions, then cooled to room temperature, after solid-liquid separation, rinse the black solid with deionized water until neutral, then filter, and air-dry to obtain a magnetic cobalt catalyst with a mass percentage of cobalt of 11%;

(2) Take 0.7g of melamine, 0.07g of sodium hydroxide and 0.07g of magnetic cobalt catalyst and mix them evenly in a crucible, put the crucible in a muffle furnace and heat it up to 550°C for 4 hours, and get the mass percentage of cobalt after natural cooling 1.2% black powder insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst.

The application of the insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst of the present invention in catalyzing Oxone to degrade levofloxacin wastewater is characterized in that the specific process is: under room temperature conditions, 10mL of Oxone solution with a molar concentration of 0.01mol/L The mass percentage content of 0.005g cobalt is 1.2% black powdery insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst composition oxidation system joins in the levofloxacin waste water that 50mL mass concentration is 10mg/L, 20min degradation efficiency is 96.68%, the insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst is recovered by filtration or centrifugation and recycled again.

The insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst prepared by the present invention has good insolubility in neutral environment, good catalytic performance and certain photocatalytic performance, and can be applied to difficult biological Degradation of organic pollutants. At room temperature, the oxidation system composed of 10mL Oxone solution with a molar concentration of 0.01mol/L and 0.005g of insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst with a mass percentage of 1.2% cobalt was added to a 50mL mass concentration In 10mg/L levofloxacin wastewater, the degradation efficiency was 96.68% in 20 minutes. The present invention synthesizes gC ₃ N ₄ materials with controllable nitrogen defects in one step by simple alkali assistance. The synthesis method can obtain a series of gC ₃ N ₄ samples with different nitrogen defect concentrations with the change of raw material ratio, and the band gap can be in The continuous controllable adjustment between 2.7-2.3eV greatly broadens the visible light absorption capacity of gC ₃ N ₄ , and greatly improves the visible light catalytic efficiency.

Description of drawings

Figure 1 is a 200nm SEM image of the insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst prepared in Example 4. It can be seen from the figure that the regular lamellar structure is defective gC ₃ N ₄ , and the spherical particles are loaded on the defective gC 3 N 4 Cobalt catalysts with magnetism on the gC ₃ N ₄ sheet structure;

Figure 2 is a 200nm SEM image of the insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst prepared in Example 4. It can be seen from the figure that the particles are small spherical, with an average particle size of 150nm, and these particles are stacked together.

Detailed ways

The above-mentioned contents of the present invention are described in further detail below through the embodiments, but this should not be interpreted as the scope of the above-mentioned themes of the present invention being limited to the following embodiments, and all technologies realized based on the above-mentioned contents of the present invention all belong to the scope of the present invention.

Example 1

(1) Dissolve 2.703g FeCl ₃ 6H ₂ O, 2.780g FeSO ₄ 7H ₂ O and 6.033g CoSO ₄ 7H ₂ O in 20mL of deionized water. After the dissolution is complete, an orange-red mixed solution is obtained. The above mixed solution Put it in a water bath and heat it to 60°C and add it dropwise to 45mL of ammonia solution with a molar concentration of 3mol/L. During the reaction, black solids are produced. After the reaction, the turbid liquid containing a large amount of black solids is ultrasonically Ultrasound at 60°C for 30 minutes under the same conditions, then cooled to room temperature, after solid-liquid separation, rinse the black solid with deionized water until neutral, then filter, and air-dry to obtain a magnetic cobalt catalyst with a mass percentage of cobalt of 11%;

(2) Take 0.7g of melamine, 0.07g of sodium hydroxide and 0.07g of magnetic cobalt catalyst and mix them evenly in a crucible, put the crucible in a muffle furnace and heat it up to 550°C for 4 hours, and get the mass percentage of cobalt after natural cooling The black powdery insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst with a content of 1.2% is ground for use.

(3) At room temperature, 0.005g of insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst was added to 50mL of 10mg/L levofloxacin solution, and the mixed solution was placed on a magnetic stirrer for degradation, almost no longer degraded after 42min , and the degradation efficiency was 7%.

Example 2

(1) Dissolve 2.703g FeCl ₃ 6H ₂ O, 2.780g FeSO ₄ 7H ₂ O and 6.033g CoSO ₄ 7H ₂ O in 20mL of deionized water. After the dissolution is complete, an orange-red mixed solution is obtained. The above mixed solution Put it in a water bath and heat it to 60°C and add it dropwise to 45mL of ammonia solution with a molar concentration of 3mol/L. During the reaction, black solids are produced. After the reaction, the turbid liquid containing a large amount of black solids is ultrasonically Ultrasound at 60°C for 30 minutes under the same conditions, then cooled to room temperature, after solid-liquid separation, rinse the black solid with deionized water until neutral, then filter, and air-dry to obtain a magnetic cobalt catalyst with a mass percentage of cobalt of 11%;

(2) At room temperature, 10 mL of Oxone with a molar concentration of 0.01 mol/L was added to 50 mL of a levofloxacin solution with a mass concentration of 10 mg/L, and the mixed solution was placed on a magnetic stirrer for degradation. After 45 minutes, there was almost no degradation , and the degradation efficiency was 3.13%.

Example 3

(1) Dissolve 2.703g FeCl ₃ 6H ₂ O, 2.780g FeSO ₄ 7H ₂ O and 6.033g CoSO ₄ 7H ₂ O in 20mL of deionized water. After the dissolution is complete, an orange-red mixed solution is obtained. The above mixed solution Put it in a water bath and heat it to 60°C and add it dropwise to 45mL of ammonia solution with a molar concentration of 3mol/L. During the reaction, black solids are produced. After the reaction, the turbid liquid containing a large amount of black solids is ultrasonically Ultrasound at 60°C for 30 minutes under the same conditions, then cooled to room temperature, after solid-liquid separation, rinse the black solid with deionized water until neutral, then filter, and air-dry to obtain a magnetic cobalt catalyst with a mass percentage of cobalt of 11%;

(2) Put 0.1.77g of melamine, 0.177g of sodium hydroxide and 0.07g of magnetic cobalt catalyst into a crucible and mix evenly, put the crucible into a muffle furnace and heat it up to 550°C for 4 hours, and after natural cooling, the mass of cobalt is obtained. The black powdery insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst with a content of 0.5% was ground for later use.

(3) At room temperature, add 10 mL of Oxone with a molar concentration of 0.01 mol/L to 50 mL of levofloxacin solution with a mass concentration of 10 mg/L, and then add 0.005 g of insoluble magnetic cobalt with a mass percentage of 0.5% cobalt/ Defective gC ₃ N ₄ composite catalyst was degraded by placing the mixed solution on a magnetic stirrer, and the degradation efficiency was 73.9% in 60 minutes.

Example 4

(1) Dissolve 2.703g FeCl ₃ 6H ₂ O, 2.780g FeSO ₄ 7H ₂ O and 6.033g CoSO ₄ 7H ₂ O in 20mL of deionized water. After the dissolution is complete, an orange-red mixed solution is obtained. The above mixed solution Put it in a water bath and heat it to 60°C and add it dropwise to 45mL of ammonia solution with a molar concentration of 3mol/L. During the reaction, black solids are produced. After the reaction, the turbid liquid containing a large amount of black solids is ultrasonically Ultrasound at 60°C for 30 minutes under the same conditions, then cooled to room temperature, after solid-liquid separation, rinse the black solid with deionized water until neutral, then filter, and air-dry to obtain a magnetic cobalt catalyst with a mass percentage of cobalt of 11%;

(2) Take 0.7g of melamine, 0.07g of sodium hydroxide and 0.07g of magnetic cobalt catalyst and mix them evenly in a crucible, put the crucible in a muffle furnace and heat it up to 550°C for 4 hours, then get the mass percentage of cobalt after natural cooling The black powdery insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst with a content of 1.2% is ground for use.

(3) At room temperature, add 10 mL of Oxone with a molar concentration of 0.01 mol/L to 50 mL of a levofloxacin solution with a mass concentration of 10 mg/L, and then add 0.005 g of insoluble magnetic cobalt with a mass percentage of 1.2% cobalt/ Defective gC ₃ N ₄ composite catalysts were degraded by placing the mixed solution on a magnetic stirrer. After 20 minutes, there was almost no degradation, and the degradation efficiency was 96.68%.

Example 5

(1) Dissolve 2.703g FeCl ₃ 6H ₂ O, 2.780g FeSO ₄ 7H ₂ O and 6.033g CoSO ₄ 7H ₂ O in 20mL of deionized water. After the dissolution is complete, an orange-red mixed solution is obtained. The above mixed solution Put it in a water bath and heat it to 60°C and add it dropwise to 45mL of ammonia solution with a molar concentration of 3mol/L. During the reaction, black solids are produced. After the reaction, the turbid liquid containing a large amount of black solids is ultrasonically Ultrasound at 60°C for 30 minutes under the same conditions, then cooled to room temperature, after solid-liquid separation, rinse the black solid with deionized water until neutral, then filter, and air-dry to obtain a magnetic cobalt catalyst with a mass percentage of cobalt of 11%;

(2) Take 0.3g of melamine, 0.03g of sodium hydroxide and 0.07g of magnetic cobalt catalyst and mix them evenly in a crucible, put the crucible in a muffle furnace and heat it up to 550°C for 4 hours, and then get the mass percentage of cobalt after natural cooling The black powdery insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst with a content of 2.4% is ground for use.

(3) At room temperature, add 10 mL of Oxone with a molar concentration of 0.01 mol/L to 50 mL of a levofloxacin solution with a mass concentration of 10 mg/L, and then add 0.005 g of insoluble magnetic cobalt with a mass percentage of 2.4% cobalt/ Defective gC ₃ N ₄ composite catalyst was degraded by placing the mixed solution on a magnetic stirrer, and the degradation efficiency was 77.7% in 60 minutes.

Example 6

(1) Dissolve 2.703g FeCl ₃ 6H ₂ O, 2.780g FeSO ₄ 7H ₂ O and 6.033g CoSO ₄ 7H ₂ O in 20mL of deionized water. After the dissolution is complete, an orange-red mixed solution is obtained. The above mixed solution Put it in a water bath and heat it to 60°C and add it dropwise to 45mL of ammonia solution with a molar concentration of 3mol/L. During the reaction, black solids are produced. After the reaction, the turbid liquid containing a large amount of black solids is ultrasonically Ultrasound at 60°C for 30 minutes under the same conditions, then cooled to room temperature, after solid-liquid separation, rinse the black solid with deionized water until neutral, then filter, and air-dry to obtain a magnetic cobalt catalyst with a mass percentage of cobalt of 11%;

(2) Take 0.1g of melamine, 0.01g of sodium hydroxide and 0.07g of magnetic cobalt catalyst and mix them evenly in a crucible, put the crucible into a muffle furnace and heat it up to 550°C for 4 hours, then get the mass percentage of cobalt after natural cooling The black powdery insoluble magnetic cobalt/C ₃ N ₄ composite catalyst with a content of 5.0% is ground for use.

(3) At room temperature, add 10 mL of Oxone with a molar concentration of 0.01 mol/L to 50 mL of a levofloxacin solution with a mass concentration of 10 mg/L, and then add 0.005 g of insoluble magnetic cobalt with a mass percentage of 5.0% cobalt/ Defective gC ₃ N ₄ composite catalyst was degraded by placing the mixed solution on a magnetic stirrer, and the degradation efficiency was 46% in 60 minutes.

The above embodiments have described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What are described in the above embodiments and description are only to illustrate the principles of the present invention. Without departing from the scope of the principle of the present invention, there will be various changes and improvements in the present invention, and these changes and improvements all fall within the protection scope of the present invention.

Claims (2)

1. the preparation method of insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst is characterized in that concrete steps are: (1) Dissolve 2.703g FeCl ₃ 6H ₂ O, 2.780g FeSO ₄ 7H ₂ O and 6.033g CoSO ₄ 7H ₂ O in 20mL of deionized water. After the dissolution is complete, an orange-red mixed solution is obtained. The above mixed solution Put it in a water bath and heat it to 60°C and add it dropwise to 45mL of ammonia solution with a molar concentration of 3mol/L. During the reaction, black solids are produced. After the reaction, the turbid liquid containing a large amount of black solids is ultrasonically Ultrasound at 60°C for 30 minutes under the same conditions, then cooled to room temperature, after solid-liquid separation, rinse the black solid with deionized water until neutral, then filter, and air-dry to obtain a magnetic cobalt catalyst with a mass percentage of cobalt of 11%; (2) Take 0.7g of melamine, 0.07g of sodium hydroxide and 0.07g of magnetic cobalt catalyst and mix them evenly in a crucible, put the crucible in a muffle furnace and heat it up to 550°C for 4 hours, and get the mass percentage of cobalt after natural cooling 1.2% black powder insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst. 2. the insoluble magnetic cobalt that method as claimed in claim 1 makes/defective gC ₃ N ₄ application of composite catalyst in catalytic Oxone degradation levofloxacin waste water, it is characterized in that concrete process is: under room temperature condition, with 10mL molar concentration The oxidation system composed of 0.01mol/L Oxone solution and 0.005g of cobalt insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst with a mass percentage of 0.005g of 1.2% was added to 50mL of 10mg/L In levofloxacin wastewater, the degradation efficiency was 96.68% in 20 minutes, and the insoluble magnetic cobalt/defective gC ₃ N ₄ composite catalyst was recovered by filtration or centrifugation and recycled again.